Deep South vs geographic region

Deep South and geographic region both are nouns.

Word	Noun	Adjective	Verb	Adverb
Deep South	Yes	No	No	No
geographic region	Yes	No	No	No

Deep South (noun)	geographic region (noun)
the southeastern region of the United States: South Carolina and Georgia and Alabama and Mississippi and Louisiana; prior to the American Civil War all these states produced cotton and permitted slavery	a demarcated area of the Earth